Device-to-Device (D2D) communication in a cellular communications network is receiving a significant amount of interest, particularly with respect to next and future generation networks. D2D communication is communication between a source device and a target device, where both the source device and the target device are wireless devices (e.g., User Equipment devices (UEs) in 3rd Generation Partnership Project (3GPP) terminology). Some of the potential advantages of D2D communication include off-loading of the cellular network, faster communication, increased awareness of surrounding wireless devices of interest (e.g., running the same application), higher-quality links due to a shorter distance, etc. Some appealing applications of D2D communications are video streaming, online gaming, media downloading, Peer-to-Peer (P2P), file sharing, etc.
A D2D capable wireless device (e.g., a D2D capable UE) may be simultaneously configured to: (1) receive cellular signals on the Downlink (DL) carrier frequency and (2) receive D2D signals of other D2D capable wireless devices on the Uplink (UL) carrier frequency. The UL and DL carrier frequencies may belong to the same frequency band or to different frequency bands. The D2D capable wireless device may not be able to simultaneously receive both types of signals (i.e., cellular signals and D2D signals) due to a limited amount of receiver resources at the D2D capable wireless device. A receiver resource is characterized by radio front end resources (e.g., a Radio Frequency (RF) power amplifier, RF filters, etc.) and/or baseband resources (e.g., processors), memory, etc. This results in a scenario where the D2D capable wireless device can effectively use its receiver resources for only one of the two types of operations at a given time, i.e., the D2D capable wireless device can use its receiver resources for either D2D operation or for cellular operation at a given time.
The ability to receive only DL cellular signals or only D2D signals at a given time degrades the overall system performance. For example, the D2D capable wireless device may miss scheduling of data on a cellular link while receiving D2D signals. A network node (e.g., the serving base station of the D2D capable wireless device) will be unaware of the fact that D2D capable wireless device has missed certain data blocks on the cellular link due to D2D reception. Therefore, such missed packets/data blocks will be retransmitted to the D2D capable wireless device after missed reception is detected by the higher layer protocols, e.g. Radio Link Control (RLC), Internet Protocol (IP), etc. This increases the packet transmission delay and also degrades the link adaptation of the cellular DL scheduling channel (e.g., Physical Downlink Control Channel (PDCCH)). To compensate for the missed PDCCH, the network may increase the resources for PDCCH (e.g., control channel elements and/or transmit power). This in turn will consume more resources for PDCCH and will in turn reduce cellular DL capacity and/or increase interference on those resource elements.
In light of the discussion above, systems and methods are needed to avoid or minimize the loss of reception of data by a D2D capable wireless device on a cellular link as well as on a D2D link.